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Neoplasms
| Image = | Caption = | DiseasesDB = 28841 | ICD10 = - | ICD9 = - | ICDO = | OMIM = | MedlinePlus = 001310. | eMedicineSubj = | eMedicineTopic = | MeshID = D009369 }} specimen containing a malignant neoplasm, namely an invasive colorectal carcinoma (the crater-like, reddish, irregularly-shaped tumor)]] of the uterus]] Neoplasm (from ancient Greek νεο- neo-'', "new" + πλάσμα ''plasma, "formation", "creation") is an abnormal mass of tissue as a result of neoplasia. Neoplasia is the abnormal proliferation of cells. Prior to neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia. However, metaplasia or dysplasia do not always progress to neoplasia. The growth of neoplastic cells exceeds, and is not coordinated with, that of the normal tissues around it. The growth persists in the same excessive manner even after cessation of the stimuli. It usually causes a lump or tumor. Neoplasms may be benign, pre-malignant (carcinoma in situ) or malignant (cancer). In modern medicine, the term tumor means a neoplasm that has formed a lump. In the past, the term tumor was used differently. Some neoplasms do not cause a lump. Classification *ICD-10 Chapter II: Neoplasms *International Classification of Diseases for Oncology *WHO classification of the tumors of the central nervous system Types A neoplasm can be benign, potentially malignant (pre-cancer), or malignant (cancer). * Benign neoplasms include uterine fibroids and melanocytic nevi (skin moles). They are circumscribed and localized and do not transform into cancer. * Malignant neoplasms are commonly called cancer. They invade and destroy the surrounding tissue, may form metastases and eventually kill the host. Potentially malignant neoplasms include carcinoma in situ. They do not invade and destroy but, given enough time, will transform into a cancer. * Secondary neoplasm refers to any of a class of cancerous tumor that is either a metastatic offshoot of a primary tumor, or an apparently unrelated tumor that increases in frequency following certain cancer treatments such as chemotherapy or radiotherapy. Of interest to psychoplogists are: * Brain neoplasms * Breast neoplasms * Endocrine neoplasms * Eye neoplasms * Nervous system neoplasms Difficulty of definition Because neoplasia includes very different diseases, it is difficult to find an all-encompassing definition. The definition of the British oncologist R.A. Willis is widely cited: "A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues, and persists in the same excessive manner after cessation of the stimulus which evoked the change."Willis RA. The Spread of Tumors in the Human Body. London, Butterworth & Co, 1952 This definition is criticized because some neoplasms, such as nevi, are not progressive. Clonality Neoplastic tumors often contain more than one type of cell, but their initiation and continued growth is usually dependent on a single population of neoplastic cells. These cells are presumed to be clonal – that is, they are descended from a single progenitor cell. Sometimes, the neoplastic cells all carry the same genetic or epigenetic anomaly that becomes evidence for clonality. For lymphoid neoplasms, e.g. lymphoma and leukemia, clonality is proven by the amplification of a single rearrangement of their immunoglobulin gene (for B cell lesions) or T-cell receptor gene (for T cell lesions). The demonstration of clonality is now considered to be necessary to identify a lymphoid cell proliferation as neoplastic. It is tempting to define neoplasms as clonal cellular proliferations but the demonstration of clonality is not always possible. Therefore, clonality is not required in the definition of neoplasia. Neoplasia vs. tumor Tumor (Latin for swelling, one of the cardinal signs of inflammation) originally meant any form of swelling, neoplastic or not. Current English, however, both medical and non-medical, uses tumor as a synonym of neoplasm. Some neoplasms do not form a tumor. These include leukemia and most forms of carcinoma in situ. The presence of tumors in one part of the body can affect others. Paraneoplastic syndromes are a group of such disorders. See also *Antineoplastic drugs *Benign neoplasms *Breast neoplasms *Carcinoma vs Sarcoma *Caregiver burden in cancer caregivers *Digestive system disorders *Dysplasia *Endocrine neoplasms *Gastric system disorders *Hyperplasia *Leukemias *Liver disorders *Neurofibromatosis *Nervous system neoplasms *Oncology *Paraganglioma *Paraneoplastic phenomenon *Terminal cancer References Category:Histopathology Category:Oncology Category:Physical disorders Category:Physical health psychology Category:Neoplasms